Sennheiser Consumer Audio HD 650 – Audiophile Hi-Res Open Back Dynamic Headphone, Titan

What can I say about these headphones? These are the best cans for their price and honestly well above it. When you first put them on you’re greeted by a heavy clamp. To fix this, I extended the metal piece to adjust the headband and bent them outwards. The metal is what can withstand this so don’t bend the plastic headband, it’ll snap! The thick velour still gives a bit on a grip as your ears will certainly be making contacting with it but because the cans are oval shaped it shouldn’t be too bad.After you get over the clamp, you realize how smooth and forward the mids are. It was fun and great and all but it sounded so muffled. I was disappointed to begin with. From there, I ran some pink noise for only about 20 hours or so to burn them in. Did it change the sound significantly? No. But what it did help with is to bring out some detail and helped me get used to the sound faster. The biggest change you’ll have to get used to coming from bright headphones is the clarity is not forward and sharp, but rather it’s present but not the star of the show. You’ll hear pretty much all the detail you’d care for but it’s much quieter and subdued in the background. This leaves you with just the vocals, and boy do they sound silky smooth. You’ll be able to easily hear every word and jarring treble or poorly mastered tracks will be greeted with forgiveness on these. Basically, all your music will sound good.Jazz sounds particularly good with these as do slow songs as they fit it’s personality great. Pair these with a good amplifier, I recommend the Valhalla 2 for an entry level or a Ragnarok if you can afford it for solid state. Honestly, these could be your end game if you prefer the sound signature.For me, I still wasn’t convinced as I knew the comfort could be improved and I wanted more detail. I ruined a good thing by doing so. The rings that hold the pads onto these cans are glued so I took some scissors and ripped them off. I replaced these cans with the HD700 pads just to try. The comfort instantly increased but the bass quantity went way down (while the quality of the bass picked up, it was much more speedy and less bloomy than with the stock pads), the detail and treble went way back up and to my surprise the mids recessed a tiny bit but not by much. This could probably be fixed with tubes. Doing this pad swap though took away everything that made the 650s magical to begin with. They really do change the sound so I recommend sticking with the stock velours or equivalent if you like the bassy/warm mid forward sound signature of the stock 650s. I certainly do so I will be buying them again (they are overpriced though, they basically are velour stitched over memory foam that you could take off some old packaging, $50 is a bit too much for pads but I guess they had to add up the costs to equal the total sum they’re charging for this can).So who is the 650 for? If you can’t afford $1,000 cans but want sweet vocals and impactful bass (not crazy deep but rich and heavy when necessary) then the 650s are definitely up your alley. It’s super forgiving so lossy files will not be a problem here nor will poorly recorded music (which is a good thing in my books as it gives you time to build up your higher quality collection). I would not recommend these headphones if you want airyness, lots of detail or clarity. Those are best reserved for the 600s, 700s or 800s.Where’s the upgrade from here? Pre-fazor LCD2 or LCD2-C or the Atticus. You’ll need some beefy hybrid/SS amps for those but they are indeed a better upgrade as their soundstage, mids, and overall bass are better with a bit better clarity (not night and day).To wrap things up, the warm sound is not for analyzing your music. It’s for relaxing as you go about your day, it’s for enjoying lyrics, it’s for sipping some coffee while writing up a paper. Details are fun but I finally have found my preferred sound signature. Bright sound signatures will fatigue your ears after a while with all the detail and glaring sharpness and as a result, I think a warm sound will fit most everyone’s preferences unless you’re in the camp that wants to hear every last detail in your music. I’m just glad I heard truly warm cans and not just cans outfitted with some warmth to truly get an idea of the experience you get and that is one of just fun, relaxing, shivers down your spine with well recorded music. These things will love tubes! Get some Mullards, Telefunken, Philips Milliwatts, or Gold Pin 6NPC’s for some additional warmth and less of a dry sound. Pour that syrup!

All my life I hate headphones, because I couldn’t listen to them longer period of times in ear canal ones were piercing my brain over on ear ones were uncomfortable with side effects my ears were sweating itching. Experience made me refuse buy any headphones over the decade because I’ve always felt they not worth it. Other hands I have quite old vintage Pioneer Hi-Fi Speakers which is my uncle bought in 80’s. They still sounds great but only goes to frequency response 28 KHZ max. I have approximately 105 SACD ripped them to DSD ( Sony DSF) format with my old PS3, sacd ripper, Also Around 203 Hi-Res albums ( 24 BIT) which my friends & I bought shared through different online stores like ( Hdtracks, Qobuz, Hiresaudio.com etc). Rest of my collection just Redbook 16 bit 44.1 khz lossless format ), I haven’t decent DSD native decoding DAC I’m using Macbook Pro 15. ( 2016) this device Audio capabilities garbage it has Cirrus Logic DAC muddy which only goes 96 khz, line out from this device only limited 48 khz max feeding this device through line out to amp to speakers were awful experience everything sounds muddy instruments sound separation, soundstage nothing is presents Hi-Res Audio sounded worth than CD etc. I have before Sony SACD player it laser head malfunctioned after 8 years of Use & went bad 8 years ago. After this thing broken from different laptops even expensive Apple Macbook Pro audio experience was worst I’ve experienced so far. I knew I need some sort of USB Audio Advanced DAC something to convert my DSD files Natively & Hi-Res Audio max out of resolution doesn’t make sense have 24 bit 192 khz lossless file when your device DAC only can reproduce 96 khz can only output 48 khz max so you got my point. I have proper DAC now which Capable Play DSD ( 64,128) natively PCM up to 384 khz & line out headphone out not limited to 48 khz anymore it is alo headphone amp which have specs 285 mv ( 32 Ohm) 2.9 volt.1. Sennheiser HD 650 Comfort ———– I would give 10/10 never used anything like this before, you can listen for longer periods without getting any fatigue or discomfort they also very well breathable, I’m using this about 5-6 hours without break I’ve never got tired this is so big advantage this headphones have over others & what make them so special best in their class ( Note they have little clamping force in beginning when they are new but this thing easily resolved after 4 days of Use I left them on position Clamping Box 10 cm distance from each drives 4 days all day & this clamping pressure has gone)2. Sennheiser HD 650 Sound Quality & Resolution ———– Second batch of this product which is currently Amazon.com selling have frequency response up to 10 – 41.000 hz ( Hi – Res Audio Certified By Japan Audio Society) it has sticker on box, Sound quality resolution everything crystal clear bass in there ( Mids Vocals I’ve never heard anything like this they are magical & very straight forward & intimidate this headphones only woth buying just for listening female vocals they sounds so precious nothing come close this kind of quality this cans providing in this regard), Highs many others would say veiled actually I’m not agree with that they very well represented they just not piercing this is one of the magic formula which makes listen to this headphones long listen sessions without getting tired.3. Sennheiser HD 650 -Power Requirement DAC, Amplification, Source ————- This headphones rated 300 ohm, Power requirement for this I’m not 100 % sure but checked online headfi.org other online 3 volt 500 mv – 32 ohm, everyone says they incredible scales with powerful amp. I’m currently using them with my 2.9 volt 285 mv on 30 ohm source they driving this in required level so they sounds incredible, I’ve not t feeding them all 500 mv by now I don’t own so powerful headphone amp yet. I bet with powerful amp they even getting better. Of Course Source material DAC also matters it will help get better results in the end. Currently my source 1200 ( 16 bit 44.1 khz albums lossless format), 105 DSD SACDS, 203 Hi-Res 24 Bit ( 44.1 khz up to 192 khz files) 150 albums I have in ITunes format 256 kb/s ACC, In my listening best sounding is DSD, 2nd place 192 khz PCM, 3 rd place Redbook CD 16/44.1, worst sounding AAC 256 kb/s . During listening sessions I’m more often trying avoid this ACC albums. So source matters as well to get full more detailed refined experience.4. Sennheiser HD 650 – value build quality ————— This headphones lightweight for it own class so you couldn’t expect this thing being build from any metal it have metal where durability matter Driver Grills made from metal headband clamping sides made from metal, rest of the Unit it is high quality plastic. If you take a good care about your equipment I didn’t think it will be broken anytime soon some people using HD 600 now over 15 years & nothing got broken during this time except pads & cable this is normal. This thing Made In Europe Ireland how many items do you own last 2 decades made in Europe ? Trust me build quality it is top notch. For 374.99 $ this headphones is steal. This is 500 $ valued headphones for the resolution comfort this thing provide I don’t think they overpriced, nowadays any sub par Sony or Other HI-RES headphones costing 250 $ forget about bluetooth other futures every other headphone have sound quality through wireless option worst indeed, still best option connection for optimal sound quality is wire.Audio Software Used for testing Audio Nirvana Plus full version only available by this moment only ON MAC OS costing 74.99 $, It is bitperfect software have Lots of Audio futures & excellent sound quality 10 times better what average ITUNES sounds like, Native DSD playback, advanced metadata editing etc.I’m usually not to keen write reviews about products but I then saw some people giving this item sub par scoring one star rating so I decide wrote one. Please don’t listen to this people they don’t using this headphone as intended. They generally bought it plugged into smartphone jack or laptop, in my experience this headphone I’m not tried my smartphone but from Macbook Pro 15 ( 2016) headphone jack they sound like some cheap 15 $ no name headphone. So Please note ( Source, DAC, proper amp, all this matters to get full out of this headphones)

HD 650Heavenly sonic bliss. My favorite headphone. Full rich, lush sounding voices and instruments. Widest sound stage of my headsets with excellent clarity. Very easy to separate and follow various voices and instruments in the music I listen to. Very balanced across the entire range of frequencies without one range over powering another. Everything is very clear. No muddiness of sound. Cybals and chimes crisp and clear. Snare drums nice crisp sound. Bass pleasant with excellent sound decay and appropriate reverberation lasting longer than my other headsets. I can really feel the music around my ears with this headset. The sound envelopes my head instead of feeling like its between my ears. Now I can experience the music rather than just listen to it. Makes music much more enjoyable and realistic sounding. This can be driven by my iPod, iPad, MacBook Pro, Laptops and Desktop PCs without an amplifier. I have no doubt an amplifier will improve the sound, but the sound is already rich and clear without amplification and still better than my other headphones. I’m hearing/experiencing things that I never heard before with my other headsets … the faint pops that occur from an old LP that has been digitally recorded … just amazing (from an iPod without amplifier).This is my experience. Your mileage may vary depending upon what you want out of your headsets.Finding the “best headphone” is a very expensive and very subjective journey. Reading reviews can only take one so far. Opinions range far and wide depending upon the reviewers individual tastes, experience with music and what one primarily listens to. Descriptions of the sound in reviews don’t always help due to differences in meaning. For example what is described as the veiled Sennheiser sound may be what I call a mellow laid back sound (not sure). My advise is listen to your music with a lot of different headphones and do your own comparisons to determine what you like. What you hear coming from each headphone is going to vary with the design of the headphone, but also modulated bya. the type of music you listen tob. how the recording was originally made (microphones converting analog to electrical then stored on magnetic tape or digitized)b. the quality of the recording you are listening to (especially if digitized, what was truncated if anything)c. the format in which it is recorded and sampling rated. the equipment you play it on and how it translates the recording back to an electrical impulse to be sent to the headphonee. the headphones themselves (open, closed, type of diaphragm material, how many speakers (i.e. the Shure 500 series has 2 woofers and a tweeter in each ear piece to achieve its balanced sound presentation across its spectrum, I have a gaming headset with multiple speakers)Having said that, the music I listen to is classical to 60s, 70s, 80s, 90s, pop, country, jazz, big bands, vocals, instrumentals.I don’t have a dedicated amplifier and play all my headphones on iPods, iPads, iPhones, Mac Book Pros, PCs, Pioneer Tuners. All my headphones sound just fine without an amplifier, but I have no doubt that an amplifier will improve the sound.My music is recorded in MP3 at 320 kbps, but I prefer M4A apple lossless or WAV at 1400 kbps for the best possible digital sound quality. I can hear the difference between 1400 kbps, 320 kbps, and the more compressed music at 192 and 128 which can be found on MP3 sites like the apple store. I convert my CD collection to both 1400 kbps and 320 kbps 44.1 MHz so it can be played at the best quality on whatever system I am using.All my headphones have been broken in with at least a 72 hour continuous play run.My headphones from most favorite to least favorite areSennheiser HD 650Shure 500PTHSennheiser HD 598AKG K550Sennheiser HD 555 modified to 595Sony DLP777 — brightJaybird Spirit — midtones muffled due covering that prevents sweat getting into ear piecesSennheiser HD 280Noise cancellers:Bose QC2 — bass heavy, muddy midtonesBose QC3 — even more bass have, muddy midtonesDr. Dre Beats — too bass heavy, stick to rap and non-critical listening (rap)For me, the HD 650 is a 5 star headphone and by far my favorite of all my headphones. Allows me to truly feel and experience the music I like listening to using the devices I have. My iPods, iPhone, iPads and MacBook Pro can drive this 300 ohm just fine (of course the volume level has to be turned up compared to the lower ohm headphones), but the lush rich realistic sound still comes through better than the other headphones.By feel, I mean that the HD650 diaphragms move so much air around my ears I can feel and experience the music as opposed to just hearing it. The Shure PTH500 can do this in my ear canal. My HD598 does this much better than the HD 555 and has a more pleasant sound to me than the HD555. But none of these come close to the experience I get with my new HD650. It’s like standing in front of a speaker at a concert or DJ’d party except its around me ears instead of having my body feel the sound wave.The timbre, tone, character of the instruments from the HD650 is slightly better than my original reference PTH500. PTH500 and HD650 are better than my other headsets. With these two, I discovered things that I couldn’t hear with the other headsets. Sound stage of the HD650 is wider than the PTH500 which is wider than the other headphones. Both have much better separation of the instruments and vocals and much better clarity which gives the music a more 3 dimensional enjoyable sound. Much easier to pick out individual instruments and so I can more easily play along on piano, guitar etc. With other headsets I have to struggle to hear the individual parts. The Shure 500 has been my favorite reference headphone since 2008. With its sound isolation qualities, I use it when traveling and when I don’t want to disturb others around me. The problem with it is that it can eventually be painful on the ear canals and sound quality (bass) is lost when the ear canal seal is lost when moving around or exercising. Additionally, hearing the crunch of food while eating and listening with the 500s is a consequence of in ear monitors.Both the HD650 and PTH500 have the best balance across all sound frequencies with the widest sound stage. The Bose QC2, QC3, and Beats have more emphasis on bass followed by treble at the expense of midtones, so if I want really loud bass, I’ll go with the Beats followed by QC3, then QC2 for lesser degrees of bass punch.The HD 598 was my favorite after the PTH500 because its open design moves a lot of air allowing me to kind of feel the music, but not the extent of the HD650. It has what I consider a more laid back and mellow sound than the HD 555 and PTH500. Kinda relaxing and pleasant.HD555 DLP777 place more emphasis on treble. If I want high energy treble, the HD555 and AKG K550 are my go to headsets.I prefer the open design over the closed headsets because they just move air better with a generally richer sound then my closed headphoneShure 500PTH — best overall balance and 3D clarity while physically blocking outside noiseHD 598 — open, good overall balance, mellow soundAKG 550 — closed, good overall balance. doesn’t move air as well as HD598, but good second choice to the 598HD 280 — closed thin; waste of my money. was never happy with it.Sony MDP 777 — closed, emphasis on trebleBose QC2 — closed moderate bass. muddy midtonesBose QC3 — closed heaviest on bass. muddy midtoneSo my choices for headsets boil down toBest overall sonic experience: HD650Best outside noise reduction/isolation and overall sonic experience: Shure 500 seriesBest to minimize noise spill into the surrounding environment when I can’t use the Shure 500: AKG 550Best for heavy bass emphasis: In order from least bass to intense bass: Bose QC2, QC3, Dr. Dre BeatsUltimately the “best” headset is a subjective opinion depending upon what you want to hear and/or experience out of your music. There is a huge sliding scale of perceived quality. I wouldn’t recommend spending much on an expensive headset if your music is 128 kbps compressed. But then again, it is cheaper to just buy 1 headset and grow into it rather than spend lots of money working ones way up to the holy grail of headsets. If I knew then what I know now, I would have just bought the HD650 and stopped there.

In this technical review I will explain and gives a few examples why the HD650 are the excellent headphones that they are. I’ll also dispel a few misconceptions about its performance. Initially, I was unsure whether it was really worth buying these expensive (unfortunately now even more expensive) headphones, since the HD650 has earned a special reputation on certain large forum sites on the Internet. Apparently the HD650 is great, but at the same time is “veiled”, with a “dark sound signature”; it’s also “hard to drive”, “picky about amps, scaling with more expensive amps into the >$1000 territory”. It created confusion in me and I thought to myself if all that really makes any sense. So I first researched electro-acoustic principles on an informative blog and learned some truth that made logical sense. Then I finally purchased it.Cosmetically, the HD650 has a nice clear-coat finish over the titanium-silver (actually pearl grey) color scheme, where the small multi-colored sparkly flecks of paint can be seen around sunlight. Even the outer side of the grille gets the sparkly treatment, while the inner side is bare stainless steel. The stock cable (which is just fine BTW!) is thick and very supple. It only has subtle low frequency microphonics when tapping it with fingers, and none when it’s rubbed against clothing. The fit of the headphones is secure, and stays put during left/right and angled up/down head movements. The somewhat strong initial clamping force lessens over time. The modular construction of the headphones makes disassembly easy. For instance, tilting the ear cups downward a bit past the resistance as if trying to lay them flat unsnaps the upper half of the ring from the central hubs. Once the upper half of the ring is then pulled out, place the ear cup in your lap with the cable entrance side facing you, and using your fingers in that area, firmly push away the lower trim piece which simultaneously causes the grille to come off as well! Replacing the headband pad is simple. (Remove the capsules beforehand.) I managed to get the edge of my thumb just behind the Made in Ireland plastic stopper and pushed it out quickly and forcefully. Then extend the metal band until it comes out. Repeat for the other side. Now slide the pad out. It is not glued on. To reassemble, first carefully feed the edge of the pad all the way through the narrow groove of the plastic arc. Then put the left and right bands through the second groove behind the pad and snap back in the stoppers.Now, with all that out of the way, the best and easiest way to evaluate headphone performance is with 20Hz to 20kHz sine wave sweeps (download the logarithmic one at audiocheck.net) and pink noise. If it sounds even and clean, then that would carry over into normal use, since sine waves are the basic building blocks of sound reproduction. Similarly, a TV display’s performance is seen with gray-scale linearity, RGB coordinates for gamut accuracy close to BT. 709, white balance targeted to 6500K, etc. If it performs well there, such a display would be accurate for normal program material. For audio, the sine wave sweep should not contain frequency sections that get your attention in terms of peaks, valleys, ringing or other anomalies. I’m happy to report that the HD650 has a remarkably even and linear response during the sweep! The so-called “mid-bass hump” isn’t even perceived as being louder than the 500Hz area. A critical area (especially for female voice and higher notes from strings and wind instruments) is from around 700Hz to 3kHz. It is totally even there! The HD650 does a fantastic job in that portion of the spectrum as it’s incredibly natural and transparent sounding. It’s also very easy to hear the treble frequencies become finer sounding during the upward progression. Pink noise is smooth and balanced. It’s virtually impossible to discern any imbalance between the higher frequency portion of the noise with the lower frequency portion. I would like to point out that the compensated frequency response graph at Inner Fidelity shows a 15dB notch around 5 to 6kHz compared to 1kHz. But actually there is no audible recession of 15 decibels in that area when listening to the sweep! It is flat when listening by ear. That notch is responsible for these headphones not imparting harshness and sibilance. There is a slight audible dip at about 7kHz and another at 10kHz. But after that the high treble is actually nicely extended and present, especially in the 12 to 16kHz region. At the other end of the spectrum, the deep bass lacks a few dB of rumble in the lowest octave. Overall, the HD650 has a substantially flat response and a lifelike timbre. And the HD650’s wonderful transient response can be attributed to its high frequency extension, high damping factor from the amplifier for the lower frequencies, and the low mass aluminum coil. Everything is critically damped.I also conducted a comparison with the HD598 and HD428. The HD598 lacks the bass response, bass weight, fuller body of the low mids to the start of the upper mids (200Hz to 750Hz) of 650. But the 598 gets into big trouble with the lower treble and beyond. I can detect a bit of a dip after 1kHz and then there are a couple of sharp audible peaks and a bit of shrillness from around 2kHz to 5kHz with an indistinctness over all the high frequencies afterwards. Its pink noise has some emphasis in that area (the ‘tssshhh’ sound), with the lower frequencies being slightly quieter. Hence, its sonic character is lean and bright in the upper mids and transition to the low treble. It’s easy to notice that female vocals don’t have a natural timbre and cymbals lack detail compared to the HD650. Onto the HD428. A little bit of distortion and looseness is heard in the lower bass area but progresses quite evenly until around 3 to 4kHz where it has quite a big noticeable drop, and comes back up to about 10kHz and then gently rolls off the rest of the highs. Its pink noise is tilted towards warmth with the lower frequencies a bit louder than the higher ones. Though Headroom’s graph shows a weak bass response for the HD428, it does not take into account how the human ear interprets low frequency resonance inside the closed ear cups. (A quick sweep or 3 second chirp also reveals an echo-knock inside the right cup). Bass is quite tight, but lacks real impact or weight (except for the fabric material tickling the ears), even though it gives the impression of a little more bass than the 650 due to resonance (but that resonance affects the perception of low frequency transients). But at least the 428 does not have that harsh low and mid treble of the 598! It seems more like a 650 with a subdued, mellow or recessed response from the low treble and beyond that, but it’s a surprisingly clean sounding can for the price! Its treble is more articulate than the 598s. I think it represents a superb value along with the HD448 or HD449 and is pleasant for long listening sessions too as it doesn’t offend my ears like the more strident HD598.So now that we know the HD650 is actually very balanced in frequency response (which also relates to good dynamics), it’s on to distortion. It can be summed up briefly: This headphone’s distortion is inaudible! That means pure, clean, smooth, full-bodied sound with natural harmonics beings heard leading to accurate timbre, high resolving ability and detail retrieval since there’s no discernible garbage being introduced by the transducer. There is a clear and precise differentiation of all frequencies and octaves. Headroom’s graph for the 500Hz sine wave distortion (tested at 90dB) shows the HD650 has vanishingly low levels, lower than some other high-end headphones more expensive than it. It has a really small second harmonic and that’s about it! Higher order distortion is virtually non-existent. The HD650 is so linear that even when turning the volume up, it still doesn’t seem like it’s loud enough! The sound never gets thick or harsh. And there is no grain at all in the sound. The HD598 has some graininess in the mids and highs that is ever-present indicating odd order harmonic distortion. The HD428 isn’t grainy, but has a bit of a smoothed over thickness or lushness in the mids and lacks articulation, indicating even-order harmonic distortion. But generally, the even-order harmonics are not as offensive as the odd ones. Headroom’s graphs back up what I heard from all three. The HD650 is a real winner here.Since harmonic distortion will necessarily produce intermodulation distortion when multiples tones are present, IMD is never nice to hear. I can back this up with an example. Corona’s Rhythm of the Night R.B.X. Euro Mix is a well-mastered Eurodance song that has a strong grinding bass. Once the main bassline starts at 0:36, and particularly at 0:42, the HD598 outputs a significant amount of IMD at very high volume. The bass and treble become garbled and the song becomes an unenjoyable mess. The HD428 chokes too. Occasional pops can be heard since the smaller driver doesn’t have enough excursion capability. The HD650 is totally unfazed by the high demands, rendering the controlled bass with clarity, impact, and weight with appreciable bone conduction as slight vibrations are also felt through the front teeth when both rows are touching. I do not recommend listening at such high volumes for any extended length of time for obvious reasons. In fact, I hear more nuances in the music at more moderate to low volumes. It may not be as stimulating that way, but it’s better quality listening.I also found three easy examples of frequency response differences among all three cans! In the CD Maxi Single of DJ BoBo’s Somebody Dance With Me, at the female vocal section “I’ve got this feeling, somebody dance with me!”, the words “feeling” and “me” are emphasized. With the HD428, they are recessed in amplitude and thus a bit dull and lacking in dynamics. With the HD598, that pitch is where a narrow peak occurs, so it’s shrill and bright sounding there. And with the HD650, the response is perfectly balanced with controlled dynamics. Likewise, with 2 Unlimited’s No Limits, the female vocal part “There’s no limit!” the “limit” is a similar pitch to the above example and will exhibit the same thing. Again, the HD650 has such a wonderful and natural timbre in the critical high mids. And an easy example of the HD598’s emphasis in the upper mid to low treble transition is Sonic the Hedgehog 3’s spin-dash sound effect. It is very loud and strident. On the HD650, it’s so clean, balanced, and it’s easy to hear the real clarity and “fineness” of that sound. Now which headphone is more veiled? 😉 There’s no hype in the highs with the HD650. Hyped-up highs seem to be the new audiophile Flavor of the Times.In terms of source material requirements, lossless files or 320kbps MP3s would provide optimal sound quality. 128kbps MP3s sound thinner, particularly in the bass and midrange, due to the missing data. Also, songs whose average volume range from about -12dB to -18dB FS will showcase the excellent micro and macro dynamics and effortless sound projection of these headphones. The majority of pop, rock, and dance music up to the mid-1990s hover in that range, whereas nowadays most music is unfortunately compressed to a loud overall level with hardly any dynamic range.Next up is the physical inspection of the transducers. The HD650’s 40mm Duofol diaphragm (part number 600129 minisys) has a large dome with a noticeably spherical or rounded surface area. Although the dome’s diameter is slightly larger than the HD598’s, the latter’s dome is flatter and deflated looking in comparison to the 650’s. The HD428 has a very tiny dome and voice coil (the latter seems to be only about 10mm), which will naturally limit its bass performance.The last section is the awesome spatial sound. With the HD650 the stereo image is psycho-acoustically perceived as occurring in a free and open space. It is instantly recognized by the auditory system like so. I get no sense of the ear cups creating any sort of boundary to the sound. Whether it’s real-life acoustic or synthesized music, I can sense the soundstage size of all the different songs I have in a realistic way that’s absolutely natural and also true to the source.Don’t get too caught up in Sennheiser’s marketing when they say 45 degree angled baffles by themselves automatically create a speaker-like sound as that may create a sighted or expectation bias. There’s a near negligible difference in the radiating point of a mono signal when I listened to angled (HD598) and straight (HD650) baffle design headphones. Yet the HD650 easily beats the HD598 in width, depth, height, and separation even though it doesn’t have angled drivers. I’ll explain why the spatial sound is superb. The 650 has close-tolerance drivers (max. 1 dB difference) meaning both left and right channels have nearly identical phase (time) and frequency (amplitude) response, which are required for good imaging. So in that regard, the HD650’s transducers are reproducing the electrical signal (i.e. the source) with much greater accuracy. Pink noise is perfectly centered without the slight shift towards the left like on the other two headphones. The sine sweep is also centered all the way from 20Hz to 20kHz and does not pan to the left and right with the upper mids and treble like the lower-end models. And compared to the other models, during stereo playback the HD650 has a solid phantom center that is present (thanks to the constantly centered sine sweep), while the left and right channels are simultaneously heard separately just outside the pinna (instead of in the ear). Remember that “stereo” is derived from the Greek word for “solid.” And what’s solid is what’s in the middle.Elaborating a bit further on the previous statements, the center portion of the mix is *distinct* and is experienced as *separate* from other sounds that are placed towards the left and right while they are *simultaneously* occurring. The asterisks denote the differences between the HD650, which has precision-manufactured drivers, and the HD598, which does not. For example, in Madonna’s “Dress You Up”, the beginning part where she says “you’ve got style” there are reverb tails of “style” at the left and right that are separate from the main center with the HD650, but not with the HD598. Any slight pan or shift during the sweep will result in lack of stability in stereo imaging performance. For instance, in Phil Collins’ Another Day in Paradise, during the chorus, “Cause it’s another day for you, you and me in paradise” the HD428 shifts the “me” to the left of center compared to “you”, since the former is an upper mid sound while the latter is a lower mid sound. The HD650 has no flaws here. And phase information in the music (e.g. reverberations from the instruments in the hall in classical music) seem wide open. And the totally open chassis design further allows the sound to radiate out without contributing its own reflections.The HD650’s earcups utilize a polyamide 6 and glass-fiber construction (PA6 GF) that is quiet and solid when the gloss black portion adjacent to the earpads is lightly tapped with a fingernail. Likewise, only that nice distinctive stainless steel clang can be heard when tapping on the grille when the headphones are worn or held. Doing the same thing to the HD598 (which utilizes conventional ABS plastic) reveals a hollow plastic sound. Indeed, this attribute (lack of resonances in the housing) along with the aforementioned driver matching contributes to the sense of transparency in the HD650’s stereo imaging, in that a pure audio image that consists only of time and level differences is formed in the mind.It’s also finally worth mentioning that the HD650, since its distortion is so low, will reveal the relatively high distortion from tube amps. So this “scaling with expensive amps” mentioned in the opening paragraph essentially means listening to the various amounts of second harmonic distortions of tube amps. I personally would recommend pairing the HD650 with a nice solid-state amp. It doesn’t matter how much that amp costs, but about getting one that measures well (flat response, no distortion or noise), has near zero output impedance, and provides enough voltage (anything in the 2 to 3 volts RMS range is absolutely sufficient) for a powerful and exciting dynamic range. In the audio industry, higher priced gear does not always translate into better performance. This industry has some strange things going on now, like ridiculous price differences between the high-end models. Considering I bought the HD428, HD598, and HD650 new from Amazon last year for $50, $180, and $350 respectively, it seems a bit odd for the next two models to cost $1000 and $1500.The HD650 has a full and well-balanced frequency response, extremely low distortion with its clean, pure, and smoothly detailed sound even at very high listening levels. It has no discernible diaphragm or earcup resonance which would otherwise produce a peak in the mid-range or treble response and has a wonderful, naturally open spatial sound. Sennheiser may never voice a reference headphone this nicely ever again or at least for a long time to come. What more is there to ask? The HD650 easily satisfies the criteria for true high-fidelity reproduction.

I own around 8-10 different headphones and earphones that range in brands, price, styles, etc… I’ve tried Klipsch, Bose, Sennheiser, V-Moda, Audio Technica, Beats, Apple, AKG, Samsung, Sony, Skullcandy, etc… I do enjoy listening to a large variety of music and I do like premium headphones but I am in no way an audiophile. The brand I always seem to go back to for more has always been Sennheiser. It all started with the HD558 open back headphones. It was my first experience with open back headphones and I really liked it. I found myself hearing so much more than I had ever heard in my favorite music. Now after using the HD650 for a while I feel I can offer a decent impression for someone considering purchasing these headphones.While many people will surely disagree(audiophiles I’m looking at you), you can technically drive these headphones with your phone or mobile music device. It does have 300ohm impedance, but the sensitivity of the drivers is such that you can get enough volume to “hear” music. It is almost loud enough and I imagine for many people it will be enough. However, the HD650 may as well be a cheaper pair of headphones if all you’re going to do is plug these into your phones because the listening experience takes off when these cans are driven properly. Whereas you can hear music through them on your phone you can actually listen to music when you have these driven.My setup is fairly simple and somewhat low end still. In fact I imagine that I haven’t had a chance to fully appreciate my headphones yet. I am using the Schiit Fulla 2 DAC/Amp and plugging in my iPhone 7 Plus with the camera adapter through usb into the Fulla 2 and have listened to lower quality music files, Apple Music 256kbps, and Tidal lossless 1.4Mbps files. While there are a lot of entry level DAC/Amp or Amp solutions I think the Fulla 2 is excellent in its quality, power, ease of use, and options.The build quality is good and while it does use a lot of plastic it feels durable. What I really appreciate about Sennheiser and specifically these headphones is that while everything feels durable it is also all replaceable. You can replace the headband, the head cushion, the ear pads, the cable, and you can order it all from Sennheiser directly. I like owning a product that I know I can maintain and I appreciate not having to send it to Sennheiser to fix every little thing. I have owned a lot of headphones that use cheap plastic that cracks, pleather that flakes and peels, and rubber coatings that wear and get sticky. Then you call the companies and they either don’t make the parts at all or used to but don’t anymore because they don’t make the product any longer. The design of the HD650 has been used from at least the HD600 and longer than most millennials have been alive. In fact they kept the tried an true design for their new HD660s so they’ll have parts for years to come.Speaking of tried and true, they are that way because for one the design has worked acoustically for them but also the design has led to one of the most comfortable headphones ever made. They can take an adjustment period and for people with big heads like myself, I recommend fully extending the earpieces and flexing the metal band the relax the clamp force on your head. There are instructions online for how to do this safely or you could always stretch them out over a box to loosen them up a bit. If the clamp is too strong or not either way you’ll end up with a very nice and comfortable fit. The ear pads are a nice velour material and the foam is appropriately soft and spongy. The head cushion is a very silky material and the foam is very soft. I really like that it has a small gap right at the top of your head to prevent that from being a hot spot of discomfort right on all of the blood flow in that area. After working my set in I find them easily wearable for hours and hours without discomfort although the ear pads can get a little warm if you’re in a hot area. After putting them on your head I recommend just tweaking the rotation of the ear cups until they feel right.In my experience with these headphones I have been very impressed. In fact it may be the most enjoyable music listening experience I’ve ever had. The HD650 is described as the most colorful in the HD6 line but compared to most of the headphones I have used before, it comes off as pretty neutral and well balanced. The mids are a bit forward compared to the lows and highs but it feels natural to my ears. It is a warmer, darker, slower, and thicker experience but it’s smooth and rich. I know it sounds like I’m describing eating dark chocolate but it is a bit like Dark chocolate for your ears. The level of detail is great and it is just very easy on the ears. I enjoy listening to music on my HD650’s and I actually do so more than anything else so far. If you’re looking for bass, I’d keep looking. These are open back headphones and while the bass is very nice and well defined they are not gonna punch you in the face like a bass head would like.Comparing them to my HD700’s I would recommend getting these because while the HD700 is maybe technically a better headphone it is sometimes too analytical and the spikes in the high end can make listening to them a little tiring. If you just wanted to listen to classical music then the HD700’s are amazing and better than the HD650 in my opinion but overall the HD650’s feel more versatile and more enjoyable for all types of music.If I had to make any complaints about the HD650 it would have to be the wire connections and the stiffness of the adjustment on the ear cups. The headphones were nice enough to put the Braille letter L on the left side but the cable has no such thing. The connection point is a two prong termination that has to go a specific way on a specific side. They do have a small raised L and R respectively on each side and the raised letters are meant to face outward. The problem is seeing and feeling the raised letters to tell which is which. If you’re in good light and have decent vision then it is easy enough to see. However if lighting isn’t great and/or your vision isn’t perfect you’ll have a hard time telling which is which. To make matters worse you can potentially damage the cable termination or the headphones if you plug them in incorrectly. The three bump Braille “L” on the left side would have been an easy solution to this, especially considering they’ve already used it on the ear cups.Another issue is the stiffness of the adjustment band. Sizing these headphones perfectly is required for maximum comfort. You ideally want both sides to be more or less equal lengths and to the right position so the headband isn’t putting too much pressure on your head and the ear cups sit well over your ears. Trying to adjust the headband is a bit of an inconvenience because to start with it is stiff and hard to pull out one click at a time. The best way to do this is to grab the metal portion towards the ear cup and pull away from the headband. Also there are no markers indicating the adjustment so you can’t be quite sure if both sides are equal or in the right spot until you put them on and then resize them. Another minor gripe but something that seems easy to address.I feel the HD650 is around or just past entry level audiophile headphones. If you’re looking to upgrade to these from something like a HD558 or 598 I would say go to an audio store that can provide you with a burned in set of headphones with good quality DAC/Amp and the listen to the kind of music you like. Considering these really only come alive with the right equipment driving them I think testing these out beforehand is the only way to go. Also, if you really do like these headphones the HD6XX from Massdrop have come around 3 times or so for $200. They are basically the HD650 rebranded and selling for $200 and I think that’s a steal.The HD650’s might change the way you feel about music. They might allow you to explore songs you’ve heard hundreds of times but in ways you never knew. They also may not do any of that for you, but if you appreciate music I think you just might appreciate these too.